I forgot the exact title of this story, but I believe it got up to chapter six before the author just stopped it. Basically, a kid wakes up in his dorm room in a parallel universe and this girl birsts in and just starts fucking him in a frenzy. This is because periods are different in this universe. Anyhow, the mystery of the story was that the MC has a father who was believed to have been a part of this alternate universe, and as the MC learns about the universe, information connects his father to a shady organization.
Does this ring any bells? From what I can remember it didn't receive any reviews on the toplist, so therefore people may not have scene it.